Lifting-jack



A. PETELER.

LIFTING JACK.

APPLICATION FILED MAR.25,1920.

L3 MQW Patented 001;. n, 1921.

M 2 SHEETS-SHEET1.

A. PETELER.

LIFTING JACK.

APPLICATION FILED mmzs, 1920.

2 SHEETS-SHEET Z.

L39 4m 4 Patented Oct. M, 1921.

gb N ieeaaaa.

To all whom it may concern.

Be it known that I, ADOLPH PETELER, a citizen of the United States, residing at 147 Denhoft' avenue, Freeport, county of Nassau, and State of New York, have invented certainnew and useful lmprovementsin Lifting-Jacks, fully described and represented in the following specification and the acbar step by step, or lowering it step by step,

or dropping the bar entirely. J

. The invention comprises .a bell-crank pivoted adjacent to the detent and constructed to engage a stud upon the detent, and a revers crank pivoted by the side of the lifting-pawl and having a body by which it can be moved, and an arm'to contact withthe bell-crankfor retracting the detent in lowering the rack-bar.

The constructionis such that a stud upon the'lifting-pawl may act upon the reverse crank and impart an accelerated and multipliedmovement to the detent by its bellcrank. j j l l M The construction and operation ofrthese parts will be understood by reference to the annexed drawing, in whichiFigure' 1 is a side elevation of a ack provided with the improvement, and the cover-plate of the casing removed; Fig. 2 is. a section of the casing on line 2 2 in Fig.1; Fig. 3 isyadiagram showing the adjustment of the parts for lowering the rack-bar step by step; Fig. 4 is a diagram showing the adjustment of the parts to Wholly retract Iboth' pawls, so as to permit'the freemovement of the rack-bar by hand; Fig. 5 is a section of the casing taken on line 5-5 in Fig. 4; and Fig. 6 is a sec- $011 of the casing taken on line 66 in in14.

designates the standard of the jack with casing B at the top,and the rack-bar C slides through thesame; v, i

A hand-lever D-is pivoted in the lower corner of the casing andgca'rriespthe liftingpivoted upon a fixed pivot c in the'upper part of'the casing. i

Specification of Letters Patent.

into the rack-teeth C.

Patented ta. ii, 1921.

Application filed March 25, 1920 Serial No. 568,779.

The pawls shown in Figs. 2 and. 5 lie in one side of the casingand are separated by alpartialpartition f from a space 9 in the opposite side of the casing, .in which the mechanism is mounted for varying the ad- ;justment of the parts to raise, lower, or

drop the lifter-bar. v

A stud a projects from the pawl a into the space 9 and a reverse crank is pivoted upon a pivot 70 in such space, and its body E extended across the side of thepawl a to cooperate with the stud. Its outer end projects'beyond the casing to form a handle for movingitjas desired.

. This member is termed a reverse crank because it is used to reverse the action of the ciated with each of the pawls, but the one associated with the lifting-pawl is termed a reverse crank to distinguish it from the one journaled with the detent upon the pivot 0. a V

A springv e presses the pawl a normally A bell-crank having arms 0 and 0", is

'journaled upon the pivot c of the detent,

and a stud 6 projects from the detent across the plan of the bell-crank, as shown in Figs. 2 and 5. A spring e is applied to the pivot c and the stud b and presses the detent b normally toward the. teeth of the rackbar. A spring e is applied to the bell-crank and the pivot c to press the arm 0 forcibly toward the stud b of the detent, the spring of the bell-.crankbeing made stron'ger than the spring 6 of the pawl, sothat the bellcrank when unrestrained presses the detent away from the raclcbar. The arm 0 of the bell-crank extends toward the reverse crank E, which is also of right-angle or bell-crank form and has a lever-arm h directed toward the detent so as to contact with the arm '0, when the body of the reverse crank is swung downwardly, as shown in Fig. 1. The arm h in such case rotates the bell-crank upon the pivot a and retracts it from contact with the stud b of thedetent, thus leaving the detent free to press intothe teeth of the rack-bar. pawl; a. The holding-pawl or detent b is Itywill'be noticed in the drawing, that the arm 0 is made very much shorter than the armg h so as to multiply the angular movewhich permit-s it to promptly engage the nearest tooth upon the. rack-bar. I

' The" body "of the reverse crank projects through a" slot in one edge of the casing, and may be-locked in its lower position by con tact with a shoulder v2' upon the side of the --s lot. The top of the slot forms an upper stop 3.

'Aspring Z is appliedto the pivot and the arm h of the reverse crank to press such arm normally away from the arm 0 of the bell-crank, andoperates to press the body E against the upper stop y' when the reverse crank is not locked in its lower position. The spring Z yields in lowering the rack-bar step by step, as the stud a upon the lifting-pawl contacts with the bodyE' and depressesit at each downwardmovement of the pawl, as hereinafter described.

Operation of the (Zerice.

The reverse crank is locked in its lowest position for raising the rack-bar step by step, as such adjustment presses the arm it against the arm 0 of the bell-crank and re tracts the arm 0 from the stud of the detentas shown in Fig. 1, leaving the detent free to move under the control of its spring 6, when catching each tooth of the'rack as pawl. 7

The reverse crank remains stationary during such use of the ack, and the stud of the lifting pawl .does not contact at all with the body of the re'verse'crank.

' In lowering the rack-bar step by step it is they are successively raised by the liftingnecessaryto engage the detent with the rack-teeth while the load is resting upon the lifting-pawl, and this is effected by unlocking the reverse crank and leaving it to move upwardand downward under the control of the stud a and the spring Z. V

Under these conditions, the stud a when the lifting-pawl is moving downward, con- 7 tacts withthe body E of the reverse crank close to its fulcrum, thus tipping or rocking the reverse crank momentarily, so that its arm hmoves the'belhcrank from the position shown by full lines in Fig. 3 (in which position it holds the detent from engagement with the rack) to the position shown in dotted lines, in which the detent is left free under the control of its spring 6 to engagethe successive teeth of the rack.

A clearance notch m is cut in the top of the reverse bell-crank adjacent to the point where the Stud a press'esnpon such body,

and the continued downward movement of the liftingpawl when the rack is arrested by the detent causes such lifting-pawl to slide outwardly upon the rack-teeth and bring the stud a over the notch m. This removes the pressure of the arm it upon the bell-crank, and leaves the reverse crank free tomove under the control of its spring Z.

This action of the stud a upon the reverse crank occurs when the rack-bar is carrying a load, but when it is carrying no load the lifting-pawl does not exert sufiicient pressure upon the body of the reverse crank to turn it upon its pivot against the resistance of the bell-crank.

The spring 6 of the bell-crank is made to exert a considerable force to overcome the resistance of the pawl-spring c, and the bell-crank therefore remains stationary under these conditions, holding the detent out of engagement with the rack as shown in full lines in Fig. 3.

lVhen the lifting-pawl draws out of the rack-teeth (when moved downward by the hand-lever) the rack is immediately freed from both of the pawls and may be moved upward or downward freely by hand without opposition from the pawls.

It will be observed that the bell-crank and reverse crank act directly by pressure upon one another, and wear and friction are thus avoided which arise when sliding, contacts are employed. Thus, the bell-crank pushes directly against the stud b (in retracting the pawl b) and the arm h presses directly against the bell-crank arm 0 in retracting the pawl Z) from the rack-teeth.

It will be observed that all the springs likewise press directly against the pants that they move, and are made of spiral coils which are cheaper and retain their elasticity for a longer time than fiat leaf-springs, and have a greater range of movement.

The prime object of my invention is to change the detent from an inoperative position (retracted from the rack-teeth) quickly to an operative position in readiness to engage any of the rack-teeth by releasing: the detent quickly from the mechanism which holds it inoperative.

The invention differs from others in having a bell-crank associated with the detent and a bell-crank also associated with the lifting-pawl, the latter being so connected with the former as to produce an increased and accelerated movement of the bell-crank which holds the detent inoperative. This movement of the bell-crank releases the detent instantly upon the downward movement of the lifting-pawl to engage a succeeding teeth of the rack.

The construction is very cheap, as there are only two principal parts employed to operate the pawls, namely, the bell-crank and the reverse-crank, which are readily required.

The operative mechanism can, without any other change, be proportioned to actu ate a jack of any desired size, large or small.

It is common in lifting jacks having a toothed rack to use a lever with a lifting pawl and to provide a detent for supporting the load, and means whereby the pawl and detent are operated reversely in raising and in lowering the rack.

Such parts are therefore public property, and my claims as in other patents upon lifting jacks cover the combination and ar rangement in which my construction difiers from those heretofore used.

Having thus set forth the nature of the invention what is claimed herein is:

1. A lifting-jack having a toothed lifterbar, a holding detent having a stationary pivotand side stud, a hand-lever with lifting-pawl pivoted thereon, a bell-crank journaled upon the pivot of the detent (1 having a long arm and spring to hold the detent in an inoperative position and a short arm for actuation, a reverse crank extended by the side of the lifting-pawl and having a multiplyingarm much longer than that upon the bell-crank to multiply the movement of the bell-crank, a stud projected from the lifting-pawl into the plane of the reverse crank and operating when the pawl is moved downward to press upon the reverse crank and turn its multiplying arm, against the arm of the bell-crank, all constructed and operated substantially as set forth.

2. A lifting-jack having a toothed lifterbar, a holding-pawl or detent 6 having a stationary pivot, a hand-lever with liftingpawl pivoted thereon, a bell-crank journaled upon the pivot of the detentand provided with a spring for holding the detent in an operativeposition, a reverse crank pivoted adjacent to the side of the lifting-pawl and having an arm to actuate the bell-crank, and means for locking the reverse crank with the bell-crank in an inoperative position.

3. A lifting-jack having a toothed lifterbar, a holding pawl or detent having a stationary pivot c, a hand-lever D with lifting-pawl pivoted thereon, a bell-crank journaled upon thepivot c of the detent and having an arm 0' and spring 6 to hold the detent in an inoperative position, and a short arm for actuation, a free-moving reverse crank E, h, extended by the side of the lifting-pawl a and having an arm much longer than that upon the bell-crank to multiply the movement of the bell-crank, a stud a projected from the lifting-paWl into the plane of the reverse crank arm E and operating when moved downward to press upon the reverse crank, the latter having a notch m to clear the stud when the liftingpawl a is wholly lowered, in the operation of releasing the lifter-bar, all constructed and operated substantially as set forth.

7 4. A lifting-jack having a toothed lifterbar, a casing with hand-lever pivoted thereon, and a lifting-pawl with journal on said lever, a fixed pivot-bearing above said journal with a detent pivoted thereon, a reverse lever extended across the lifting-pawl and pivoted upon the casing at the side of the lifter-bar, and having a crank-arm project'- ed toward the detent, and a bell-crank pivoted upon the journal of the detent, with a short arm to engage the arm of the reverse crank, and a longer arm to detachably e11- gage the detent and control its engagement with the lifter-bar.

5. A lifting-jack having a toothed lifterbar, a casing with hand-lever pivoted thereon, and a lifting-pawl with journal on said lever, a fixed pivot-bearing above said journal with a detent pivoted thereon, the pawl and detent being provided each with a side stud, and bell-cranks pivoted adjacent to the pawl and detent, and having a long arm upon one operating with a short arm on the other, to release the detent for action upon a slight movement of the lifting-pawl, the bell-cranks controlling the movement of the pawl and detent by contact of the bellcranks with their adjacent studs.

In testimony whereof I have hereunto set my hand.

ADOLPH PETELER. 

